两角度弹性阻抗反演技术在Albert湖盆非固结砂岩储层预测中的应用

Albert湖盆非固结砂岩储层发育,受物性参数变化大以及孔隙流体类型差异的影响,振幅属性和声阻抗参数无法预测储层的整体展布。岩石物理分析结果揭示泊松阻抗参数具有敏感的区域岩性判识能力,但研究区仅有小角度和中角度部分叠加资料,限制了泊松阻抗参数的有效计算。针对Albert湖盆的地质与地球物理问题,以N油田为例,提出了一套适用于非固结砂岩储层预测的两角度弹性阻抗反演方法,并在岩石物理统计分析的指导下,进一步利用纵、横波阻抗数据实现了泊松阻抗的计算,为非固结砂岩储层预测提供了数据支撑。模型试算结果验证了该方法的可行性,且实际应用效果表明,预测的砂体与实钻结果吻合较好。

Unconsolidated sandstone reservoir is well developed in Albert Lake Basin.Affected by the large variation of reservoir properties and the difference of pore-fluid types,the whole distribution of the reservoir cannot be predicted by amplitude attribute or acoustic impedance.Rock physics analysis indicates Poisson impedance parameter as the most sensitive lithology indicator in Albert Lake Basin.However,the existing two angle (small-angle and middle-angle) partial stack seismic data cannot satisfy the normal calculation for Poisson impedance.Taking N Oilfield for example,according to the geological and geophysical problems,a new method using two angle elastic impedance inversion is proposed for unconsolidated sand reservoir prediction.The Poisson impedance can be calculated using P- and S-wave impedance with the guide of rock physics analysis,which provides data base for unconsolidated sand reservoir prediction.The model test verifies the feasibility of this method and real data application shows the coincidence between the predicted sandbodies and real drilling result.

国家科技重大专项(2011ZX05030-004)资助。